This invention relates to a resin composition comprising a polyarylene sulfide resin and metal hydroxides composed mainly of magnesium hydroxide, and to a resin composition further comprising glass fibers and talc at specific compositional ratios. The composition of the present invention can give good surface appearance of molded articles, having excellent electrical characteristics such as arc resistance, etc. and can be used in wide fields, including electric, electronic parts and automobile parts.
Polyarylene sulfide resins as represented by polyphenylene sulfide resin (hereinafter sometimes abbreviated as PPS), which are excellent in heat resistance, chemical resistance, stiffness, dimensional stability, etc., have been attempted to be developed in recent years for applications in the fields where heat resistance and dimensional stability are required such as electric, electronic parts and automobile parts.
However, since said resin alone is inferior in impact resistance and mechanical strength, for the purpose of improving these properties, various proposals have been done concerning resin compositions comprising various inorganic substances formulated in said resin (e.g. Japanese Provisional Patent Publication No. 73275/1977 and Japanese Patent Publication No. 1553/1982). Further, particularly for the purpose of being used in electric, electronic parts or automobile parts, compositions improved in arc resistance have been proposed (e.g. Japanese Provisional Patent Publications No. 5252/1978, No. 162752/1979 and No. 131653/1984).
Of the inorganic substances to be used for this purpose, there have been made some proposals for the purpose of improving electrical characteristics such as arc resistance (e.g. Japanese Provisional Patent Publication No. 162752/1979). However, the inorganic substances which have been proposed up to date such as talc, clay, etc. are natural products, and are different depending on the places where they are produced and tended to be not constant in arc resistance, etc. Also, there is the method of effecting stabilization of the quality by calcining these, but the calcined product tended to be inferior in arc resistance, etc. as compared with those not calcined. Also, these exhibited a tendency that the inorganic fillers accumulate on the molded article surface to worsen the appearance of the molded article surface, when a large molded article is molded particularly by means of an injection molding machine. For this reason, it has been desired to improve the surface appearance of the molded article along with the characteristics such as arc resistance, etc. remaining as such.